When preparing figures for a manuscript it is very common to have only a single object that is the focus of attention, and in these cases it is best if the image blends seamlessly with the white background of the text.

I have been unable to figure out how to achieve this kind of effect with shadows in Karma. I have the main object (say, a torus) and a grid that I want to use as a white floor that catches shadows. I have an environment light and a spot light. I create a new Shadow Matte material and assign this to the floor, and I tried to use a light linker as a shadow mask (which was a property of the light in the /obj context) but I don't actually know how this should work.

I am pretty happy with the new LOPs workflow (especially for the relatively simple scenes I usually encounter) except for this issue about how to use the grid as a shadow catcher…

I can upload an example showing where I'm getting stuck if it would be useful.

Yes, scene please!